My own understanding is that the turning that passage is describing was motivated by, and took place after, the believing the following passage describes...
1 Thessalonians 2:13
For this cause also thank we God without ceasing, because, when ye received the word of God which ye heard of us, ye received it not as the word of men, but as it is in truth, the word of God, which effectually worketh also in you that believe.
The order is, we believe the gospel of our salvation, and then it begins to work in us to conform us to the image of Christ as we by faith turn from our old ways in obedience to the Word as to said turning from, Rom. 12:2.
Remember, these things are not always described in their chronological order, rather, according to what ever subject matter is being addressed